The subcellular organization of carbohydrate metabolism of Trichomonas vaginalis, causative agent of the sexually transmitted disease, trichomoniasis will be studied. Special attention will be paid to the relationship of this metabolism to the mode of action of antitrichomonad nitroimidazoles and to those metabolic differences which might explain the lowered aerobic susceptibility of certain T. vaginalis strains isolated from cases of metronidazole refractive trichomoniasis. These studies will include the use of several nitroimidazoles. Special attention will be paid to possible differences in the anaerobic and aerobic metabolism of these strains and to the properties of the enzymatic systems responsible for the metabolic activation of the drugs. Detailed studies on the enzymology and subcellular organization of T. vaginalis ATCC 30001 will continue with emphasis on the functional role of the hydrogenosomes and their enzymes. Metabolic balances will be determined under various conditions to assess the participation of hydrogenosomal pathways in the overall metabolism of T. vaginalis. Attempts will be made to characterize the unusual electron transport system of this organelle.